A new form of glucose-6-phosphate dehydrogenase has been isolated in pure form from the livers of starved rats, re-fed sucrose. This form has an activity of 600 plus units/mg protein compared to all previously published isolations which gave enzyme with an activity of the order of 200 units/mg of protein. While the previous "pure" form gave 3 proteins on gel electrophoresis (all with G-6-PD activity) the new form gives only one band, with traces of a higher molecular weight form. The molecular weight of the subunit of this highly active species is about 64,000. Antibody to the new active form of the enzyme has been made. It has been found that this antibody cross-reacts only poorly with palmityl Co A inactivated enzyme. These findings may change prior interpretations regarding possible nutritional induction of G-6-PD. Plans for next year include preparation of messenger RNA and characterization of this high activity form with regard to molecular weight and subunit composition. Having isolated messenger for this form of G-6-PD we plan to translate it using the wheat germ system and from there to prepare genome by reverse transcriptase. This will enable us to add to our study enzyme control via gene amplification.